JP2606548B2 - Cu wiring and method for forming the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Cu wiring which is one of semiconductor device fabrication processes and a method of forming the same.

[0002]

2. Description of the Related Art Conventionally, Al or an Al alloy has been used as a wiring material of an LSI. However, in the future miniaturization, Al or an Al alloy causes a delay in signal transmission speed due to a high resistance value and a low migration resistance. This causes a problem that the reliability is lowered. Cu is expected as a wiring material to replace Al because of its low resistance and high migration resistance. Cu
In practical use of wiring, processing, diffusion, passivation, adhesion and the like become problems.

In order to improve the adhesion, a method of forming an alloy layer with an underlayer at the interface by heating or strengthening the bonding at the interface by ion implantation has been considered. Problems remain in terms of diffusion, formation of a damaged layer, and the like. Therefore, at present, a method of preventing diffusion and improving adhesion by using an alloy layer as an underlayer of Cu is mainly used.

[0004] In the method of depositing Cu, Cu is deposited by a sputtering method or a CVD method after depositing an underlayer by a sputtering method or a CVD method. At this time, in order to prevent the wiring from having a high resistance due to the mixing of the underlayer and Cu, the underlayer deposition and C
The deposition of u is often performed in a separate apparatus.

[0005]

A method for forming a Cu wiring is to form a Cu wiring on a base insulating film or a base alloy layer by sputtering after forming the base alloy layer on the base film using an apparatus different from that for forming the base layer. . In this case, the adhesion between the Cu wiring and the underlying layer is weak, and impurities are adsorbed on the surface of the underlying layer when moving to another device, and peeling occurs to further reduce the adhesiveness, thereby reducing the reliability of the LSI. Is a problem.

An object of the present invention is to provide a Cu wiring which overcomes the above problems and has good adhesion and a method for forming the same.

[0007]

Cu wiring of the present invention, in order to solve the problems] includes a base film formed on a semiconductor substrate, a Cu _X N _1-X film formed on the underlying film, the Cu _X N _1- It characterized by having a a Cu film formed on the _X film.

In the method of forming a Cu wiring according to the present invention, an Ar gas and a N ₂ gas are simultaneously introduced on a base film formed on a semiconductor substrate to form a Cu _x N _{1 -x} layer by a reactive sputtering method. A step of forming a Cu layer by a sputtering method by introducing N ₂ gas after forming Cu _x N _{1 -x} .

[0009]

According to the present invention, a C layer is provided between the Cu layer and the underlayer.
A structure is formed in which the u _x N _1-x layer is present. The elemental element of the underlayer and Cu can be bonded via N.
As a result, the bonding force at the interface is increased, and the adhesion is improved. In addition, continuous deposition while maintaining vacuum is possible,
It is possible to prevent impurities such as O from affecting the adhesion and the resistivity.

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view of a semiconductor chip shown in the order of steps for explaining an embodiment of the present invention.

First, as shown in FIG. 1A, an Ar gas and an N ₂ gas are simultaneously supplied at 0.1 to 6 mTorr respectively, and the SiO ₂ film 20 formed on the Si substrate 10 is reactively sputtered on the SiO ₂ film 20. A Cu _x N _{1 -x} film is deposited to a thickness of 1 to 50 nm.

Next, as shown in FIG. 1B, the supply of the N ₂ gas is stopped, only the Ar gas is supplied at 0.1 to 6 mTorr, and the Cu film 40 is formed on the Cu _x N _{1 -x} film 30. Deposit 50 to 400 nm by sputtering.

The Ar gas pressure during the deposition of the Cu _x N _{1 -x} film is set at 1.
5 mTorr, N ₂ gas pressure is 1.5 mTorr, and C
When the Ar gas pressure at the time of depositing the u film is 3 mTorr, Cu
The result of the difference in adhesion between the presence or absence of _x N _1-x film 30 was evaluated by a scratch tester shown in Table 1.

[0015]

[Table 1]

[0016] Compared to the case where a Cu film is directly deposited on the SiO ₂ film, the adhesion is improved when the Cu _x N _1-x film is inserted.

The above results indicate that SiN _x was used instead of the SiO ₂ film.
It can also be obtained as a film and is applicable to all insulators. Also Si
Similar results can be obtained with any semiconductor substrate such as a GaAs substrate and an InP substrate instead of the substrate.

(Embodiment 2) FIG. 2 is a sectional view of a semiconductor chip shown in the order of steps for explaining another embodiment of the present invention.

First, S on the Si substrate 10 shown in FIG.
As shown in FIG. 2B, an Ar gas and an N ₂ gas are simultaneously supplied at 0.1 to 6 mTorr respectively on the Ti film 50 deposited on the iO ₂ film 20 at 1 to 10 nm, and the substrate temperature is set to 1
Cu _x N _1-x by reactive sputtering at 00 to 400 ° C.
A film 30 is deposited with a thickness of 1 to 50 nm. At this time, the Ti film 50 is nitrided to form a TiN film 60 having a thickness of 1 to 10 nm.

Next, as shown in FIG. 2C, the supply of N ₂ gas is stopped, only Ar gas is supplied at 0.1 to 6 mTorr, and a Cu film 40 is formed on the Cu _x N _{1 -x} film 30. Deposit 50 to 400 nm by sputtering.

[0021] As a result of the above is, SiN _x instead of the SiO ₂ film
It can also be obtained as a film and is applicable to all insulators.

Similar results can be obtained with other metals or alloys instead of the Ti film. GaAs instead of Si substrate
Similar results can be obtained for all semiconductor substrates such as s substrate and InP substrate.

(Embodiment 3) FIG. 3 is a sectional view of a semiconductor chip shown in the order of steps for explaining another embodiment of the present invention.

First, 1 is placed on the Si substrate 10 shown in FIG.
As shown in FIG. 3B, an Ar gas and a N ₂ gas are respectively applied to the Ti film 50 having a thickness of 0.1 to 6 nm.
Torr at the same time, and the Cu _x N _{1 -x} film 30 is formed by a reactive sputtering method at a substrate temperature of 100 to 400 ° C. for ₁ to 50 n.
m. At this time, the surface of the Ti film is nitrided to form a TiN film 60 of 0.5 to 10 nm, and the surface of the Ti film on the substrate side is silicided to form a TiSi ₂ layer 70 of 0.5 to 10 nm.
It is formed.

Next, as shown in FIG. 3C, the supply of the N ₂ gas is stopped, only the Ar gas is supplied at 0.1 to 6 mTorr, and the Cu film 40 is formed on the Cu _x N _{1 -x} film 30. Deposit 50 to 400 nm by sputtering.

The above results are not limited to the Ti film, and similar results can be obtained with other metals.

[0027]

As described above, according to the present invention, it is possible to provide a Cu wiring having good adhesion to a base film and a method for forming the same.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an example in which a substrate in which Ti is formed on a SiO ₂ film is used.

FIG. 3 is a cross-sectional view showing an example in which a substrate in which Ti is formed on a Si film is used.

[Explanation of symbols]

10 Si substrate _{20 SiO 2 30 Cu x N 1} -x 40 Cu 50 Ti 60 TiN 70 TiSi 2

Claims (4)

(57) [Claims] [1 claim: a base film formed on a semiconductor substrate, this and the base film Cu _X N _1-X film formed on the Cu film this Cu _X N formed _1-X film, Cu wiring characterized by having. 2. The method according to claim 1, wherein an A film is formed on the underlayer formed on the semiconductor substrate.
a step of forming a Cu _x N _{1 -x} layer by reactive sputtering by simultaneously introducing r gas and N ₂ gas, and forming a Cu layer by sputtering by introducing N ₂ gas after forming Cu _x N _{1 -x} And c. Forming a Cu wiring. 3. The method according to claim 1, wherein the under film is made of SiO ₂ or SiN _x
3. The C according to claim 2, wherein the C is Ti.
Method for forming u wiring. 4. When the underlying film is Ti, the Cu
method of forming a Cu wiring according to claim 3, characterized in that the substrate temperature during _x N _1-x deposited as 100 to 400 ° C..